The present invention relates to an antenna device used in a mobile communication system such as a PHS or the like, and a radio apparatus having the antenna device built therein.
Heretofore, a high gain was required of an antenna device used in a radio base station apparatus or fixed radio terminal apparatus in a mobile communication system such as PHS or the like. Therefore, a multistage collinear array antenna was used, for example, as shown in JP-A-5-267932, JP-A-9-232851 and JP-A-8-139521. In the antenna of this type, antennas non-directional in a horizontal plane with respect to vertically polarized wave were arranged multistageously vertically to narrow directivity in a vertical plane to thereby secure a high gain.
An end-fire array antenna represented by a Yagi antenna or a reflector-containing dipole antenna was also used, for example, as shown in JP-A-5-259733 and JP-A-8-304433. In the antenna of this type, passive elements were arranged in parallel to the direction of main radiation to thereby secure a high gain.
A broadside array antenna represented by a patch array antenna was further used, for example, as shown in JP-A-6-334434. In the antenna of this type, a plurality of antennas were arranged in a plane perpendicular to the direction of main radiation to perform distributive feeding to thereby secure a high gain.
A low-profile antenna represented by a reflector-containing loop antenna or a slot antenna was further used, for example, as shown in JP-A-6-268432 and JP-U-6-44219.
On the other hand, an antenna formed from two one-wavelength antennas arranged into the form of a square or a circle, for example, as shown inxe2x80x9cAntenna Handbookxe2x80x9d (CQ Publication Co., Ltd.) p.366 is known as a broadside array antenna mainly used in a VHF band.
In the aforementioned conventional multistageous collinear array antenna, it was however necessary to arrange a large number of antennas vertically multistageously in order to secure a high gain. For example, a height of about 1 m was needed to obtain a gain of 10 dB in a 1900 MHz band. Hence, there was a problem in making sure of the antenna-setting space and mechanical strength. Further, the antenna of this type was unsuitable for being built in a radio apparatus because of its height.
Further, in the aforementioned conventional end-fire array antenna, it was necessary to arrange a large number of antennas in the direction of main radiation in order to secure a high gain. Hence, there was a problem in making sure of the antenna-setting space and mechanical strength. Further, the antenna of this type was unsuitable for being built in a radio apparatus because of its structure.
Further, in the conventional broadside array antenna, it was necessary to arrange a large number of antennas in a plane perpendicular to the direction of main radiation in order to secure a high gain. Hence, the total area of the antenna increased, so that there was a problem in making sure of the antenna-setting space and mechanical strength. Further, the antenna of this type was unsuitable for being built in a radio apparatus because of its large area.
In addition, although the conventional low-profile antenna was formed in a small-size low-profile configuration, there was a problem that the radiation directivity could not be optimized to provide desired characteristic.
In the aforementioned antenna formed from two one-wavelength antennas arranged into the form of a square or a circle, only the radiation directivity in a predetermined vertical plane and in a predetermined horizontal plane could be obtained, and there was a problem that the radiation directivity could not be optimized to provide desired characteristic.
The present invention is designed to solve the conventional various problems generally and it is an object of the present invention to provide an antenna device in which the optimal radiation directivity can be obtained in the broadside array antenna having two one-wavelength antennas, in which a high gain and a high function can be obtained with a simple configuration and which can be used as a small-size low-profile antenna for a mobile communication system in UHF and sub-micro wave bands.
The present invention is devised so that the angle of bending in the center of each one-wavelength antenna element in a broadside array antenna having two one-wavelength antenna elements arranged therein is selected to be an optimal angle. Hence, there can be provided an antenna device in which desired radiation directivity can be obtained with a simple configuration and which has a high gain.
Further, the present invention is devised so that a plurality of antennas are connected in an opening portion at a forward end of each of the aforementioned antennas. Hence, there can be provided an antenna device which has a high gain with a simple planar configuration.
Further, the present invention is devised so that a plurality of antennas are connected in parallel with each other in a feeding portion. Hence, there can be provided an antenna device which has a high gain with a simple planar configuration.
Further, the present invention is devised so that the aforementioned antennas are formed by a pattern printed on a dielectric substrate. Hence, there can be provided an antenna device in which desired directivity can be obtained with a small-size and simple configuration and which has a high gain.
Further, the present invention is devised so that the plurality of antennas are connected to one another through transmission lines each having a predetermined electrical length. Hence, there can be provided an antenna device in which the antenna as a whole can be extended in the Y-plane direction easily, in which desired directivity can be obtained and which has a high gain.
Further, the present invention is devised so that the two pairs of aforementioned antennas are arranged with directions of main polarization perpendicular to each other and so that the antenna devices are fed with phase differences of 90 degrees. Hence, there can be provided an antenna device in which desired radiation directivity can be obtained with a simple planar configuration to achieve a circular polarization antenna having a high gain.
Further, the present invention is devised so that the two pairs of aforementioned antennas are formed by print patterns arranged on opposite surfaces of a dielectric substrate. Hence, there can be provided an antenna device in which desired radiation directivity can be obtained with a small-size and simple planar configuration to achieve a circular polarization antenna having a high gain.
Further, the present invention is devised so that a reflection plate is provided in proximity to the antenna. Hence, there can be provided an antenna device in which desired radiation directivity can be obtained with a simple planar configuration and which has a high gain.
Further, the present invention is devised so that a plurality of passive elements are provided in proximity to the antenna. Hence, there can be provided an antenna device in which desired radiation directivity can be obtained with a simple planar configuration and which has a high gain.
Further, the present invention is devised so that the aforementioned antennas are arranged as a radiator and a reflector while a plurality of wave directors each having a shape similar to that of each of the antennas are arranged in the directions of the main radiation. Hence, there can be provided an antenna device in which desired radiation directivity can be obtained with a simple configuration and which has a high gain.
Further, the present invention is devised so that the two pairs of aforementioned antennas are arranged with the directions of main polarization being made identical with each other and with the directions of main radiation being made different from each other so that the antennas are fed with phase differences of 90 degrees from each other. Hence, there can be provided an antenna device in which desired radiation directivity can be obtained with a simple configuration and which has a high gain.
Further, the present invention is devised so that the two pairs of a fore mentioned antennas are arranged with the directions of the main polarization being made identical with each other and with the directions of the main radiation being made different from each other. Hence, there can be provided an antenna device in which desired radiation directivity can be obtained with a simple configuration and which has a high gain.
Further, the present invention is devised so that the plurality of aforementioned antennas are arranged with the directions of the main polarization being made identical with one another and with the directions of the main radiation being made different from one another, and controlling is performed such that the opposite antenna elements of one or plural antenna devices among the plurality of antenna devices are partially electronically connected to each other. Hence, there can be provided an antenna device in which the radiation directivity can be changed variously with a simple configuration and which has a high gain.
Further, the present invention is devised so that a quarter-wavelength shorting stub is connected to a feeding point so that feeding is performed at a position where the impedance of the shorting stub is optimized. Hence, there can be provided an antenna device in which good impedance matching can be obtained by a small-size matching circuit with a simple configuration and which has a high gain.
Further, the present invention is devised so that an antenna device comprises a first one-wavelength slot element provided in a conductor plate so as to be bent at an angle xcex1 in the center of the first slot element, and a second one-wavelength slot element provided in the conductor plate so as to be bent at an angle xcex1 in the center of the second slot element, wherein the first and second slot elements are arranged in diamond-wise opposition to each other and wherein respective one-ends of the first and second slot elements are connected to each other to provide a feeding portion at the one-ends. Hence, there can be provided an antenna device to achieve a slot antenna having a high gain with a simple planar configuration.
Further, the present invention is devised so that, in the aforementioned slot antenna, the angle of bending in the center of each of the one-wavelength slot elements is selected to be an optimal angle to obtain optimal radiation directivity. Hence, there can be provided a slot antenna in which optimal radiation directivity can be obtained with a simple planar configuration and which has a high gain.
Further, the present invention is devised so that a plurality of slot antennas as described above are connected in the opening portion at the forward ends of the antennas. Hence, there can be provided an antenna device to achieve a slot antenna having a high gain with a simple planar configuration.
Further, the present invention is devised so that a plurality of slot antennas as described above are connected in parallel to each other at a feeding portion. Hence, there can be provided an antenna device to achieve a slot antenna in which optimal radiation directivity can be obtained with a simple planar configuration and which has a high gain.
Further, the present invention is devised so that the plurality of slot antennas are formed by a print pattern formed on a dielectric substrate. Hence, there can be provided an antenna device to achieve a slot antenna in which optimal radiation directivity can be obtained with a small-size and simple planar configuration and which has a high gain.
Further, the present invention is devised so that a reflection plate is provided in proximity to the slot antenna. Hence, there can be provided an antenna device to achieve a slot antenna in which desired radiation directivity can be obtained with a simple planar configuration and which has a high gain.
Further, the present invention is devised so that a plurality of passive elements are provided in proximity to the slot antenna. Hence, there can be provided an antenna device to achieve a slot antenna in which desired radiation directivity can be obtained with a simple configuration and which has a high gain.
Further, the present invention is devised so that the aforementioned antenna device is built in a radio apparatus. Hence, there can be provided a radio apparatus with a built-in antenna in which desired radiation directivity can be obtained and which has a high gain with a small-size and simple configuration.
Further, the present invention is devised so that a plurality of antenna devices as described above are arranged to form a sector antenna device for a radio base station. Hence, there can be provided an antenna device to achieve a diversity antenna or a sector antenna in which desired radiation directivity can be obtained with a small-size and simple configuration and which has a high gain.
Further, the present invention is devised so that a reflection plate is provided to be used in common to the plurality of antenna devices. Hence, there can be provided an antenna device to achieve a diversity antenna or a sector antenna in which desired radiation directivity can be obtained with a small-size and simple configuration and which has a high gain.
Further, the present invention is devised so that a plurality of antennas as described above are arranged to form a sector antenna device for a radio base station, and so that the sector antenna device is provided in the radio base station. Hence, there can be provided a radio base station with a built-in diversity or sector antenna in which desired radiation directivity can be obtained with a small-size and simple configuration and which has a high gain.
Further, the present invention is devised so that each of two antenna elements arranged diamond-wise is bent at an angle a in its center, and so that the angle xcex1 is selected to be an angle at which optimal radiation directivity can be obtained. Hence, there can be provided a method of controlling the directional gain of an antenna in which desired radiation directivity can be obtained with a simple planar configuration and which has a high gain.